Emergency teams fought more than 130 fires across New South Wales, the country’s most populous state, on Tuesday, with at least 40 burning out of control. Fires also continued to burn in Tasmania, after blazes at the weekend destroyed more than 20,000 hectares of land and dozens of properties.

Temperatures in some areas surpassed 45C (113F), while Monday’s average high temperature across the country set a record at 40.3C. Further record-breaking highs are expected in the coming days, with the heat so intense that Australia’s Bureau of Meteorology has been forced to add new colours to its temperature map – deep purple and incandescent pink.

The NSW rural fire service issued "catastrophic" fire warnings for four areas in the state – the most severe fire warning level.

"The word catastrophic is being used for good reason," the Australian prime minister, Julia Gillard, said on morning television. "So it is very important that people keep themselves safe, that they listen to local authorities and local warnings. This is a very dangerous day."

In the town of Tarcutta, 470km (290 miles) south-west of Sydney, designated as a "catastrophic" area, residents took refuge in the Returned & Services League – Australia’s equivalent of the British Legion, a veterans’ charity – as the blaze approached.

Gwen Brown told ABC radio that people were extremely anxious. "I’ve lived through a few things, but this is probably the scariest I’ve seen. We are just covered in smoke. There’s blue smoke and it is prominent. It would only be a couple hundred metres away," she said.

By night, Tarcutta residents were able to return to their homes, but emergency services warned them to remain on the alert. Fires continued to burn in the area.

South of Sydney, near the town of Cooma, the gateway to Australia’s ski slopes, a huge cloud of black smoke rose above the mountains. Winds gusted at up to 70km an hour, driving out of control fires close to properties. Thousands of people had been warned via text message to evacuate.

"I got a phone call at 7am to say the fire was going to impact [on] our property," Peter Evan told ABC. "We went straight out thinking that we’d mow around the house and make sure the tractor had fuel in it to make a fire break. Then we got the message to clear out. I’ve never been in a situation [like this], so it’s frightening. The smoke, you couldn’t believe the smoke."

The rural fire service’s commissioner, Shane Fitzsimmons, said the state had faced some of the worst conditions on record. "We’ve had a horrible day," he said. "We’ve seen firefighters and fire-affected communities facing the worst imaginable conditions." He praised the "extraordinary" firefighting effort in "dirty, hot difficult conditions".

In Sydney, temperatures soared to 42.3C by early afternoon. Thousands flocked to beaches and pools, and national parks around the city were closed.

The blistering heat also caused a blaze at a nuclear research facility in southern Sydney after cabling overheated in a nearby electricity substation. Thousands of homes in the city’s north experienced power outages due to soaring demand.

In the hamlet of Boomer Bay near the town of Dunalley, which was devastated by fire last Friday, thick smoke and strong winds continued to hamper emergency crews putting out spot fires. Fifteen houses were destroyed and as residents returned, they told stories of narrow escapes.

"It was like a firestorm," Merle Klug told ABC. "It came over the back. We just packed everything as quick as we could with the animals into the car and headed down to the boat ramp."

With about 25 other people, Merle and her husband, Terry, sheltered by the water as the fire burned all around.

"We couldn’t go anywhere. The heat was horrendous," Klug said. The fire had approached with incredible speed and the burnt-out shells of cars used to get to the water’s edge lay scattered across the boat ramp area, he said.

"[The fire] just come over the hill like a bullet, crackin’ in the air. And we didn’t think we’d be here [now] ourselves for the terror down there on the jetty. We thought we was goners," he said.